A method for detecting coherent light that includes configuring a spatial interferometer, receiving the coherent light through the spatial interferometer, and disposing a photo detector adjacent to the spatial interferometer. The spatial interferometer is configured such that a coherent light passing through the spatial interferometer interferes with itself. The interference of the coherent light with itself creates a light fringe. The light fringe projects onto the photo detector. The photo detector has an array of pixels operable to detect an intensity of coherent light. The array of pixels provides a plurality of outputs corresponding to coherent light received by discrete pixels of the array of pixels. The method includes determining an interference pattern of the light fringe based on the plurality of outputs of the array of pixels, and determining one or more wavelengths of the coherent light from the interference pattern.

An optical detection device and method for detecting temperature changes and/or wavelength changes of an optical probe signal includes transmitting an optical probe signal having a predetermined wavelength to an optical input port of an optical waveguide; detecting first and second optical detection signal at first and second optical output ports via first and second opto-electrical converters which create corresponding first and second electrical signals; measuring values of the first and second electrical signal and determining an absolute temperature or a temperature change of the optical waveguide and/or an absolute wavelength value or a wavelength change of the optical probe signal via values measured of the first and second electrical signals and first and second previously determined wavelengths and temperature dependencies of both first and second power transfer functions.

The invention provides a wavelength tracking system comprising a wavelength tracking unit and an interferometer system. The wavelength tracking unit has reflection surfaces at stabile positions providing a first reflection path with a first path length and a second reflection path with a second path length. The first path length is substantially larger than the second path length. The interferometer system comprises: a beam splitter to split a light beam in a first measurement beam and a second measurement beam; at least one optic element to guide the first measurement beam, at least partially, along the first reflection path and the second measurement beam, at least partially, along the second reflection path; a first light sensor arranged at an end of the first reflection path to receive the first measurement beam and to provide a first sensor signal on the basis of the first measurement beam; a second light sensor arranged at an end of the second reflection path to receive the second measurement beam and to provide a second sensor signal on the basis of the second measurement beam; and a processing unit to determine a wavelength or change in wavelength on the basis of the first sensor signal and the second sensor signal.

The present invention provides a wavelength detection device (10) provided with: a plurality of optical filters (12a, 12b); a splitting unit (11) which splits light and allows the split light to pass through each of the plurality of optical filters (12a, 12b); a plurality of light receiving elements (13a, 13b) which detect the intensities of different beams of light which have passed through the optical filters, respectively; and a calculation unit (16) which calculates, from the outputs of the plurality of light receiving elements, physical quantities related to the transmittances of the plurality of optical filters, and calculates the wavelengths of the beams of light which have passed through the plurality of optical filters, on the basis of the transmittance characteristics, wherein the transmittance characteristics of the plurality of optical filters have an inclination section in different wavelength ranges of the wavelength range of the object to be measured.

In a general aspect, a wavelength of light is measured. In some aspects, a wavelength measurement system includes an interferometer, a camera system, a sensor and a control system. The interferometer includes two reflective surfaces and a transmission medium between the two reflective surfaces. The interferometer is configured to receive an optical signal from a laser and produce an interferogram in response. The camera system is configured to receive the interferogram from the interferometer and generate interferogram data in response. The interferogram data represents the interferogram received from the interferometer. The sensor is configured to sense an environmental parameter of the transmission medium and generate sensor data in response. The control system is configured to perform operations including, receiving the interferogram data from the camera system and the sensor data from the sensor; and computing a wavelength of the laser based on the interferogram data and the sensor data.

Information relating to an etalon is accessed, the etalon being associated with a calibration parameter having a pre-set default value, the etalon being configured to produce an interference pattern including a plurality of fringes from a received light beam, and the information relating to the etalon including first spatial information related to a first fringe of the plurality of fringes and second spatial information related to a second fringe of the plurality of fringes. A first wavelength value of the received light beam is determined based on the spatial information related to the first fringe and an initial value of the calibration parameter. A second wavelength value of the received light beam is determined based on the spatial information related to the second fringe and the initial value of the calibration parameter. The first wavelength value and the second wavelength value are compared to determine a measurement error value.

This disclosure is related to devices, systems, and techniques for precisely measuring a wavelength of an optical signal. For example, a wavemeter system includes processing circuitry, a detector array, a set of optical chips, and a coarse wavelength unit configured to generate a coarse wavelength measurement of the input optical signal. The processing circuitry is configured to select an optical chip from a plurality of optical chips. The detector array is configured to generate a partial interferogram based on the at least the portion of the input optical signal. The processing circuitry is further configured to calculate an optical spectrum of the input optical signal based on the partial interferogram corresponding to the at least the portion of the input optical signal and the calibration matrix and identify, based on the optical spectrum of the input optical signal, the precise wavelength of the input optical signal.

Optical polarization-based devices and techniques are provided to enable low cost construction and easy signal processing to measure the light frequency via measurements of signals associated with a delay between the two orthogonal polarizations after passing through a DGD element and the retardation value of the DGD element without directly measuring the optical frequency. The optical detection may be designed in various configurations. In particular, for example, the optical detection may split the optical output of the DGD into two optical beams with two different optical detectors so that the final frequency information can be deducted into a pair of sine and cosine functions, such as a pair of sine and cosine functions of measured optical signal levels and the retardation value of the DGD element.

A wavelength measuring device configured to detect a wavelength of ultraviolet laser light outputted from a laser resonator with at least one etalon, the wavelength measuring device includes: a first housing having an interior space being sealed and accommodating the etalon, an input window through which the ultraviolet laser light enters to the first housing, the input window being provided at a first opening of the first housing, a first sealing member configured to seal a gap between a rim part of the input window and a circumferential portion of the first opening, a shielding film provided between the rim part of the input window and the first sealing member and configured to shield the first sealing member from the ultraviolet laser light coming from the input window, and a diffusing element provided outside of the first housing and configured to diffuse the ultraviolet laser light before being incident on the input window.

A quantitative phase image generating method for a microscope, includes: irradiating an object with illumination light; disposing a focal point of an objective lens at each of a plurality of positions that are mutually separated by gaps z along an optical axis of the objective lens, and detecting light from the object; generating sets of light intensity distribution data corresponding to each of the plurality of positions based upon the detected light; and generating a quantitative phase image based upon the light intensity distribution data; wherein the gap z is set based upon setting information of the microscope.